Transmission internal PTO clutch and method of control

ABSTRACT

A method of selectively controlling a power take-off (PTO) assembly includes positioning a clutch assembly radially between a shaft and a PTO gear, operably controlling the clutch assembly with a controller, and selectively engaging the clutch assembly with the controller. The controller monitors signals received from a plurality of sensors and compares the monitored signals with respective signal thresholds. The clutch assembly is engaged when the compared monitored signals are within the signal thresholds.

RELATED APPLICATIONS

The present application is a continuation application of U.S. patentapplication Ser. No. 15/051,891, filed Feb. 24, 2016, the disclosure ofwhich is hereby incorporated by reference in its entirety.

FIELD OF THE DISCLOSURE

The present disclosure relates to a power take-off (PTO), and inparticular to a system and method of selectively engaging the PTOthrough a clutch in the transmission.

BACKGROUND

Conventional internal combustion engine vehicles can have a PTO that ispivotally coupled to a main driveline shaft between a torque converterand the remaining portions of a transmission assembly. Many PTOs have aPTO gear that mechanically couples the PTO to a secondary assembly suchas a pump, compressor, or any other device that can utilize mechanicalpower provided by a gear. The PTO gear often has a center through-holethat is aligned with, and splined to, the main driveline. In thisconfiguration, the PTO gear will rotate whenever the main drivelinerotates.

SUMMARY

In one embodiment of the present disclosure, a PTO drive assembly for atransmission includes a shaft defining a shaft axis; a PTO gear definedradially about the shaft axis; and a clutch assembly positioned betweenthe shaft and the PTO gear and having an engaged position and adisengaged position; wherein, when the clutch assembly is in the engagedposition, torque is transferred from the shaft to the PTO gear; andwherein, when the clutch assembly is in the disengage position, torqueis not transferred from the shaft to the PTO gear.

In one example of this embodiment, the PTO gear defines an inner faceextending axially along the shaft axis, the inner face having a firstplurality of splines defined therein. In another example, the shaftdefines an outer face extending axially along the shaft axis, the outerface having a second plurality of splines defined therein. In a thirdexample, the clutch assembly includes a first plurality of plates eachdefining at least one first tang that extends radially away from theshaft axis; a second plurality of plates each defining at least onesecond tang that extends radially toward the shaft axis; a backing platespaced axially along the shaft axis on a first side of the plurality offirst plates and the plurality of second plates; an apply plate spacedaxially along the shaft axis on a second side of the plurality offriction plates and the plurality of reaction plates; and a pistonpositioned radially about the shaft axis and axially adjacent to theapply plate. In a fourth example, the piston has a thrust bearingpositioned between the piston and the apply plate.

In a fifth example, the piston does not rotate with the shaft when theclutch assembly is in either the engaged position or the disengagedposition. In a sixth example, the second tangs rotationally couple thesecond plurality of plates to the second plurality of splines along theouter face of the shaft. In a seventh example, the first pluralitysplines along the inner surface of the PTO gear are coupled to the firstplurality of plates via the at least one first tang. In an eighthexample, the piston is rotationally coupled to the PTO gear and thepiston rotates as the PTO gear rotates. In a ninth example, the PTOdrive assembly includes a hub coupled to the second plurality of splinesalong a radially inner portion and providing a receiving surface alongthe radially outer portion of the hub, the receiving surfacerotationally coupling the second plurality of plates to the shaft viathe at least one second tang. In another example, the first pluralitysplines along the inner surface of the PTO gear are rotationally coupledto the first plurality of plates via the at least one first tang. In afurther example, the PTO gear is pivotally coupled to a transmissioncase through at least one bearing.

In another embodiment of the present disclosure, a transmission having aPTO drive assembly with an internal clutch includes a transmissionhousing having a first end and a second end; a torque converter coupledto the housing, the converter configured to receive torque from a driveunit; a shaft disposed in the housing and defining a shaft axis, theshaft coupled at one end to the torque converter; a PTO drive assemblydisposed within the housing and including a PTO gear selectively coupledto the shaft; a clutch assembly disposed within the transmission housingbetween PTO gear and the shaft, the clutch assembly having an engagedposition and a disengaged position; and wherein the PTO gear rotates atthe same speed as the shaft relative to the transmission housing whenthe clutch assembly is in the engaged position; and the PTO gear doesnot rotate at the same speed as the shaft relative to the transmissionhousing when the clutch assembly is in the disengaged position.

In one example, the transmission includes a gear base disposed along aradially inner portion of the PTO gear; an cylindrical ledge alignedalong the shaft axis and spaced radially away from the shaft; and asupport disc extending radially from the cylindrical ledge to the gearbase and coupling the cylindrical ledge to the gear base; wherein, thecylindrical ledge defines a coupling surface at a radially distalportion from the shaft axis that is pivotally coupled to thetransmission case. In a second example, the clutch assembly furthercomprises a piston assembly, a first cylindrical segment aligned alongthe shaft axis and radially spaced to be proximate to the gear base; asecond cylindrical segment aligned along the shaft axis and radiallyspaced to provide a gap between the second cylindrical segment and theshaft; and a piston support disc extending radially from the firstcylindrical segment to the second cylindrical segment and coupling thefirst cylindrical segment to the second cylindrical segment; wherein anannular piston cavity is defined between the first cylindrical segment,the second cylindrical segment, and the piston support disc.

In a third example, the support disc also defines a backing plateadapted to resist axially movement along the shaft axis towards thebacking plate of one or more clutch discs disposed within the clutchassembly. In a fourth example, the second cylindrical segment defines acoupling surface at a radially distal portion from the shaft axis thatis pivotally coupled to the transmission case. In a fifth example, thesecond cylindrical segment is removably coupled to the gear base withone or more gear base splines. In a sixth example, the transmissionincludes a piston disposed in the annular disc cavity and movableaxially along the shaft axis to transition the clutch assembly betweenthe engaged position and the disengaged position. In a seventh example,the transmission includes at least one hydraulic passageway disposed inthe PTO assembly.

In a further embodiment, a transmission system includes a drive unitcoupled to an output shaft along a shaft axis, the drive unit adapted torotatably drive the output shaft; a torque converter pivotally coupledto the output shaft, the torque converter further having a PTO driveshaft coupled thereto; a transmission case pivotally coupled to thetorque converter and pivotally coupled to a PTO drive assembly; wherein,the PTO drive assembly includes a PTO gear defined radially about theshaft axis; and a clutch assembly having an engaged position and adisengaged position disposed between the shaft and the PTO gear, wheretorque is transferred from the shaft to the PTO gear when the clutchassembly is in the engaged position, and torque is not transferred fromthe shaft to the PTO gear when the clutch assembly is in the disengageposition.

In a first example of this embodiment, the PTO gear defines an innerface extending axially along the shaft axis, the inner face having afirst plurality of splines defined therein. In a second example, theshaft defines an outer face extending axially along the shaft axis, theouter face having a second plurality of splines defined therein. In athird example, the clutch assembly includes a first plurality of plateseach defining at least one first tang that extends radially away fromthe shaft axis; a second plurality of plates each defining at least onesecond tang that extends radially toward the shaft axis; a backing platespaced axially along the shaft axis on a first side of the plurality offirst plates and the plurality of second plates; an apply plate spacedaxially along the shaft axis on a second side of the plurality offriction plates and the plurality of reaction plates; and a pistonpositioned radially about the shaft axis and axially adjacent to theapply plate.

In a fourth example, the piston has a thrust bearing positioned betweenthe piston and the apply plate. In a fifth example, the piston does notrotate with the shaft when the clutch assembly is in either the engagedposition or the disengaged position. In a sixth example, the secondtangs rotationally couple the second plurality of plates to the secondplurality of splines along the outer face of the shaft. In a seventhexample, the first plurality splines along the inner surface of the PTOgear are rotationally coupled to the first plurality of plates via theat least one first tang. In an eighth example, the piston isrotationally coupled to the PTO gear and the piston rotates as the PTOgear rotates. In a ninth example, the transmission system includes a hubcoupled to the second plurality of splines along a radially innerportion and providing a receiving surface along the radially outerportion of the hub, the receiving surface rotationally coupling thesecond plurality of plates to the shaft via the at least one secondtang. In another example, the first plurality splines along the innersurface of the PTO gear are rotationally coupled to the first pluralityof plates via the at least one first tang. In a further example, the PTOgear is pivotally coupled to a transmission case through at least onebearing.

In yet a further embodiment of the present disclosure, a method ofselectively controlling the engagement of a PTO includes positioning aclutch assembly radially between a shaft and a PTO gear; operablycontrolling the clutch assembly with a controller; selectively engagingthe clutch assembly with the controller; wherein the selectivelyengaging the clutch assembly step includes monitoring, by thecontroller, signals received from a plurality of sensors; comparing, bythe controller, the monitored signals with respective signal thresholds;and engaging the clutch assembly when the compared monitored signals arewithin the signal thresholds.

In an alternative embodiment, a method of controlling a PTO assembly ofa transmission includes providing a user input, an engine, thetransmission including a shaft, a hydraulic system, and fluid within thehydraulic system having a line pressure, a controller including a memoryunit and a processor, and the PTO assembly including a PTO gear, a PTOoutput sensor, and a clutch assembly positioned between the PTO gear andthe shaft; determining, by the controller, when a user input has beenreceived; comparing, by the controller, the line pressure of the fluidto a pressure threshold stored in the memory after the user input hasbeen received; engaging the clutch assembly, by the controller, when theline pressure is above the pressure threshold; detecting PTO speed withthe PTO output sensor; and comparing, by the controller, an engine speedof the engine to the PTO speed when the clutch assembly is engaged;wherein, if a difference between engine speed and PTO speed is notwithin a predefined speed threshold value, the controller increases theline pressure.

In another embodiment, a method for controlling a PTO assembly of atransmission includes providing a controller, a user input, a pressuresensor, a valve, a shaft speed sensor, and the PTO assembly including aPTO gear, a PTO speed sensor and a clutch assembly disposed radiallybetween the PTO gear and a shaft of the transmission; receiving, withthe controller, a command from the user input indicating a desiredengagement of the clutch assembly; comparing a line pressure detected bythe pressure sensor to a pressure threshold stored in the controller;controlling the valve, with the controller, to restrict the clutchassembly from engaging the PTO gear when the line pressure is less thanthe pressure threshold; comparing a PTO speed measured by the PTO speedsensor to a shaft speed measured by the shaft speed sensor with thecontroller when the clutch assembly is in an engaged position; anddisengaging the clutch, with the controller, when the comparing a PTOspeed step indicates the PTO speed is not substantially the same as theshaft speed.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned aspects of the present disclosure and the manner ofobtaining them will become more apparent and the disclosure itself willbe better understood by reference to the following description of theembodiments of the disclosure, taken in conjunction with theaccompanying drawings, wherein:

FIG. 1 is an exemplary block diagram and schematic view of oneillustrative embodiment of a powered vehicular system;

FIG. 2 is a partial cross-sectional view of one embodiment of atransmission with a PTO clutch assembly;

FIG. 3 is a partial cross-sectional view of another embodiment of atransmission with a PTO clutch assembly;

FIG. 4a is a block diagram illustrating some of the components for acontrol system for a PTO clutch assembly;

FIG. 4b is a partial block diagram of a logic flowchart executed by acontroller in the control system of FIG. 4a ; and

FIG. 4c is a continuation of the block diagram of a logic flowchart fromFIG. 4 b.

Corresponding reference numerals are used to indicate correspondingparts throughout the several views.

DETAILED DESCRIPTION

The embodiments of the present disclosure described below are notintended to be exhaustive or to limit the disclosure to the preciseforms disclosed in the following detailed description. Rather, theembodiments are chosen and described so that others skilled in the artmay appreciate and understand the principles and practices of thepresent disclosure.

Referring now to FIG. 1, a block diagram and schematic view of oneillustrative embodiment of a vehicular system 100 having a drive unit102 and transmission 118 is shown. In the illustrated embodiment, thedrive unit 102 may include an internal combustion engine, diesel engine,electric motor, or other power-generating device. The drive unit 102 isconfigured to rotatably drive an output shaft 104 that is coupled to aninput or pump shaft 106 of a conventional torque converter 108. Theinput or pump shaft 106 is coupled to an impeller or pump 110 that isrotatably driven by the output shaft 104 of the drive unit 102. Thetorque converter 108 further includes a turbine 112 that is coupled to aturbine shaft 114, and the turbine shaft 114 is coupled to, or integralwith, a rotatable input shaft 124 of the transmission 118. Thetransmission 118 can also include an internal pump 120 for buildingpressure within different flow circuits (e.g., main circuit, lubecircuit, etc.) of the transmission 118. The pump 120 can be driven by ashaft 116 that is coupled to the output shaft 104 of the drive unit 102.In this arrangement, the drive unit 102 can deliver torque to the shaft116 for driving the pump 120 and building pressure within the differentcircuits of the transmission 118.

The transmission 118 can include a planetary gear system 122 having anumber of automatically selected gears. An output shaft 126 of thetransmission 118 is coupled to or integral with, and rotatably drives, apropeller shaft 128 that is coupled to a conventional universal joint130. The universal joint 130 is coupled to, and rotatably drives, anaxle 132 having wheels 134A and 134B mounted thereto at each end. Theoutput shaft 126 of the transmission 118 drives the wheels 134A and 134Bin a conventional manner via the propeller shaft 128, universal joint130 and axle 132.

A conventional lockup clutch 136 is connected between the pump 110 andthe turbine 112 of the torque converter 108. The operation of the torqueconverter 108 is conventional in that the torque converter 108 isoperable in a so-called “torque converter” mode during certain operatingconditions such as vehicle launch, low speed and certain gear shiftingconditions. In the torque converter mode, the lockup clutch 136 isdisengaged and the pump 110 rotates at the rotational speed of the driveunit output shaft 104 while the turbine 112 is rotatably actuated by thepump 110 through a fluid (not shown) interposed between the pump 110 andthe turbine 112. In this operational mode, torque multiplication occursthrough the fluid coupling such that the turbine shaft 114 is exposed todrive more torque than is being supplied by the drive unit 102, as isknown in the art. The torque converter 108 is alternatively operable ina so-called “lockup” mode during other operating conditions, such aswhen certain gears of the planetary gear system 122 of the transmission118 are engaged. In the lockup mode, the lockup clutch 136 is engagedand the pump 110 is thereby secured directly to the turbine 112 so thatthe drive unit output shaft 104 is directly coupled to the input shaft124 of the transmission 118, as is also known in the art.

The transmission 118 further includes an electro-hydraulic system 138that is fluidly coupled to the planetary gear system 122 via a number,J, of fluid paths, 140 ₁-140 _(J), where J may be any positive integer.The electro-hydraulic system 138 is responsive to control signals toselectively cause fluid to flow through one or more of the fluid paths,140 ₁-140 _(J), to thereby control operation, i.e., engagement anddisengagement, of a plurality of corresponding friction devices in theplanetary gear system 122. The plurality of friction devices mayinclude, but are not limited to, one or more conventional brake devices,one or more torque transmitting devices, and the like. Generally, theoperation, i.e., engagement and disengagement, of the plurality offriction devices is controlled by selectively controlling the frictionapplied by each of the plurality of friction devices, such as bycontrolling fluid pressure to each of the friction devices. In oneexample embodiment, which is not intended to be limiting in any way, theplurality of friction devices include a plurality of brake and torquetransmitting devices in the form of conventional clutches that may eachbe controllably engaged and disengaged via fluid pressure supplied bythe electro-hydraulic system 138. In any case, changing or shiftingbetween the various gears of the transmission 118 is accomplished in aconventional manner by selectively controlling the plurality of frictiondevices via control of fluid pressure within the number of fluid paths140 ₁-140 _(J).

The system 100 further includes a transmission control circuit 142 thatcan include a memory unit 144. The transmission control circuit 142 isillustratively microprocessor-based, and the memory unit 144 generallyincludes instructions stored therein that are executable by a processorof the transmission control circuit 142 to control operation of thetorque converter 108 and operation of the transmission 118, i.e.,shifting between the various gears of the planetary gear system 122. Itwill be understood, however, that this disclosure contemplates otherembodiments in which the transmission control circuit 142 is notmicroprocessor-based, but is configured to control operation of thetorque converter 108 and/or transmission 118 based on one or more setsof hardwired instructions and/or software instructions stored in thememory unit 144.

In the system 100 illustrated in FIG. 1, the torque converter 108 andthe transmission 118 include a number of sensors configured to producesensor signals that are indicative of one or more operating states ofthe torque converter 108 and transmission 118, respectively. Forexample, the torque converter 108 illustratively includes a conventionalspeed sensor 146 that is positioned and configured to produce a speedsignal corresponding to the rotational speed of the pump shaft 106,which is the same rotational speed of the output shaft 104 of the driveunit 102. The speed sensor 146 is electrically connected to a pump speedinput, PS, of the transmission control circuit 142 via a signal path152, and the transmission control circuit 142 is operable to process thespeed signal produced by the speed sensor 146 in a conventional mannerto determine the rotational speed of the pump shaft 106/drive unitoutput shaft 104.

The transmission 118 illustratively includes another conventional speedsensor 148 that is positioned and configured to produce a speed signalcorresponding to the rotational speed of the transmission input shaft124, which is the same rotational speed as the turbine shaft 114. Theinput shaft 124 of the transmission 118 is directly coupled to, orintegral with, the turbine shaft 114, and the speed sensor 148 mayalternatively be positioned and configured to produce a speed signalcorresponding to the rotational speed of the turbine shaft 114. In anycase, the speed sensor 148 is electrically connected to a transmissioninput shaft speed input, TIS, of the transmission control circuit 142via a signal path 154, and the transmission control circuit 142 isoperable to process the speed signal produced by the speed sensor 148 ina conventional manner to determine the rotational speed of the turbineshaft 114/transmission input shaft 124.

The transmission 118 further includes yet another speed sensor 150 thatis positioned and configured to produce a speed signal corresponding tothe rotational speed of the output shaft 126 of the transmission 118.The speed sensor 150 may be conventional, and is electrically connectedto a transmission output shaft speed input, TOS, of the transmissioncontrol circuit 142 via a signal path 156. The transmission controlcircuit 142 is configured to process the speed signal produced by thespeed sensor 150 in a conventional manner to determine the rotationalspeed of the transmission output shaft 126.

In the illustrated embodiment, the transmission 118 further includes oneor more actuators configured to control various operations within thetransmission 118. For example, the electro-hydraulic system 138described herein illustratively includes a number of actuators, e.g.,conventional solenoids or other conventional actuators, that areelectrically connected to a number, J, of control outputs, CP₁-CP_(J),of the transmission control circuit 142 via a corresponding number ofsignal paths 72 ₁-72 _(J), where J may be any positive integer asdescribed above. The actuators within the electro-hydraulic system 138are each responsive to a corresponding one of the control signals,CP₁-CP_(J), produced by the transmission control circuit 142 on one ofthe corresponding signal paths 72 ₁-72 _(J) to control the frictionapplied by each of the plurality of friction devices by controlling thepressure of fluid within one or more corresponding fluid passageway 140₁-140 _(J), and thus control the operation, i.e., engaging anddisengaging, of one or more corresponding friction devices, based oninformation provided by the various speed sensors 146, 148, and/or 150.

The friction devices of the planetary gear system 122 are illustrativelycontrolled by hydraulic fluid which is distributed by theelectro-hydraulic system in a conventional manner. For example, theelectro-hydraulic system 138 illustratively includes a conventionalhydraulic positive displacement pump (not shown) which distributes fluidto the one or more friction devices via control of the one or moreactuators within the electro-hydraulic system 138. In this embodiment,the control signals, CP₁-CP_(J), are illustratively analog frictiondevice pressure commands to which the one or more actuators areresponsive to control the hydraulic pressure to the one or morefrictions devices. It will be understood, however, that the frictionapplied by each of the plurality of friction devices may alternativelybe controlled in accordance with other conventional friction devicecontrol structures and techniques, and such other conventional frictiondevice control structures and techniques are contemplated by thisdisclosure. In any case, however, the analog operation of each of thefriction devices is controlled by the control circuit 142 in accordancewith instructions stored in the memory unit 144.

In the illustrated embodiment, the system 100 further includes a driveunit control circuit 160 having an input/output port (I/O) that iselectrically coupled to the drive unit 102 via a number, K, of signalpaths 162, wherein K may be any positive integer. The drive unit controlcircuit 160 may be conventional, and is operable to control and managethe overall operation of the drive unit 102. The drive unit controlcircuit 160 further includes a communication port, COM, which iselectrically connected to a similar communication port, COM, of thetransmission control circuit 142 via a number, L, of signal paths 164,wherein L may be any positive integer. The one or more signal paths 164are typically referred to collectively as a data link. Generally, thedrive unit control circuit 160 and the transmission control circuit 142are operable to share information via the one or more signal paths 164in a conventional manner. In one embodiment, for example, the drive unitcontrol circuit 160 and transmission control circuit 142 are operable toshare information via the one or more signal paths 164 in the form ofone or more messages in accordance with a society of automotiveengineers (SAE) J-1939 communications protocol, although this disclosurecontemplates other embodiments in which the drive unit control circuit160 and the transmission control circuit 142 are operable to shareinformation via the one or more signal paths 164 in accordance with oneor more other conventional communication protocols (e.g., from aconventional databus such as J1587 data bus, J1939 data bus, IESCAN databus, GMLAN, Mercedes PT-CAN).

Many PTO systems have a clutch or other means for selectively engagingthe PTO and the secondary assembly. The clutch is often located betweenthe PTO gear and the secondary assembly and is selectively engageable bythe user. The clutch is typically a separate system from thetransmission and requires a separate controller and apply an actuator.In this configuration, the clutch often transitions from a disengagedposition to an engaged position to mechanically couple the secondaryassembly to the PTO gear.

When the clutch is engaged while the driveline is rotating at anexcessive speed and the secondary assembly is stationary, the clutch candamage the secondary assembly by the sudden application of torque to thesecondary assembly. Further, the clutch may insufficiently engage if theload from the secondary assembly is too great or if insufficientengagement pressure is supplied. When the clutch is insufficientlyengaged, it may cause the clutch to fail or otherwise become inoperable.Further, a transmission control module does not always control theclutch. In this configuration, the engagement pressure supplied to theclutch may be either too weak to properly engage the clutch orunnecessarily high, wasting energy in the hydraulic system.

Referring to FIG. 2, one example is shown of a transmission and PTO gearassembly. As described above, a PTO is a device that can redirect aportion of the input power provided by a prime mover (e.g., an engine)to tools, work implements, or accessories for the purpose of performingfunctions which are secondary to the purpose for the prime mover. Forinstance, the PTO could provide power to a hydraulic pump. In a hybridsystem application, however, power or torque can flow in both directions(i.e., between inputs and outputs, rather than from an input to anoutput).

In FIG. 2, a torque converter 202 is shown coupled to a pump shaft 204.The torque converter 202 may be configured to transfer torque generatedby the drive unit 102 to the pump shaft 204. In one embodiment, the pumpshaft 204 may define a shaft axis 206 that extends longitudinally alongthe pump shaft 204. The pump shaft 204 may further be coupled to a PTOshaft 208 that is defined along the shaft axis 206. The pump shaft 204and the PTO shaft 208 may be splined to one another. However, in anotherembodiment the pump shaft 204 and the PTO shaft 208 are one integralcomponent and this disclosure is not limited to any particular shaftconfiguration.

Also disposed radially about the shaft axis 206 may be a PTO gear 210.The PTO gear 210 may define teeth 216 at a radially distal portion andbe pivotally coupled to a transmission case 212. Further, the PTO gear210 may be able to rotate about the shaft axis 206 relative to thetransmission case 212. In one embodiment, the PTO gear 210 may have agear base 214 defined along a radially inner portion of the PTO gear 210relative to the teeth 216. The gear base 214 may extend axially alongthe shaft axis 206 and extend radially inward to define a support disc216 at a front portion of the PTO gear assembly 200. In the embodimentof FIG. 2, a cylindrical ledge 218 may be spaced about the shaft axis206 to have a radius slightly greater than the PTO shaft 208. Further,the cylindrical ledge 218 may extend axially along the shaft axis 206towards the front to define a coupling surface 220 along a radiallyouter portion of the cylindrical ledge 218. In one nonexclusiveembodiment, the rear portion of the cylindrical ledge 218 may be coupledto, or integrally formed with, the support disc 216.

The PTO gear 210 may be pivotally coupled about the shaft axis 206 bythe gear base 214, the support disc 216, and the cylindrical ledge 218.More specifically, a bearing or other friction-reducing coupling meanscould be positioned between the coupling surface 220 of the cylindricalledge 218 and the transmission case 212. In this embodiment, the PTOgear 210 may rotate relative the transmission case 212 with the couplingmeans between the cylindrical ledge 218 and the transmission case 212.Further, in one aspect of this embodiment, the cylindrical ledge 218 maynot substantially contact the pump shaft 204 and/or the PTO shaft 208.Accordingly, the pump shaft 204 and/or the PTO shaft 208 may also rotateindependently of the PTO gear 210.

In one aspect of the embodiment shown in FIG. 2, a PTO clutch assembly200 is shown with a plurality of plates 222 partially disposed radiallybetween the shaft 208 and the PTO gear 210. More specifically, a firstplurality of plates 224 and a second plurality of plates 226 may beaxially aligned with the gear base 214.

In one non-limiting aspect of this embodiment, the first plurality ofplates 224 may have at least a first tang (not particularly shown)extending radially away from the shaft axis 206. The first tang may besized to correspond with one or more first spline defined in a radiallyinner face 228 of the gear base 214. More specifically, the first splinemay allow the first tang, and in turn the first plurality of plates 224,to be rotationally coupled to the inner face 228 of the gear base 214.Further, the spline may extend axially along the inner face 228 to allowat least some axial movement of the first tang along the shaft axis 206while being positing therein.

Similarly, the second plurality of plates 226 may have at least a secondtang (not particularly shown) extending radially inward towards theshaft axis 206. The second tang may be sized to correspond with one ormore second spline defined in an outer face 230 of the PTO shaft 208.More specifically, the second spline may allow the second tang, and inturn the second plurality of plates 224, to be rotationally coupled tothe outer face 230 of the PTO shaft 208 while allowing at least someaxial movement along the shaft axis 206.

A backing plate 232 may also be coupled to the second spline of theouter face 230. The backing plate 232 may have a radial stop 234 coupledto the PTO shaft 208 to define the forward most axial location of thebacking plate 232 relative to the PTO shaft 208 along the shaft axis206. The backing plate 232 may be sufficiently sized to resist axialforces applied along the shaft axis 206 towards the front withoutsubstantially deflecting. In one embodiment described in more detailbelow, an axial force may be applied to the first and second pluralityof plates 224, 226 in the forward direction by a piston 240. In thisembodiment, the backing plate 232 may substantially resist the axialforce applied by the piston 240 through the plurality of plates 222 torestrict any further axial movement along the shaft axis 206.

A piston assembly 238 may also be disposed radially about the shaft axis206 to selectively apply an axial force along the shaft axis 206. Thepiston assembly 238 may be partially defined as an annular piston cavity242 in the transmission case 212. The piston cavity 242 may partiallyencompass the piston 240 to allow the piston 240 to slide axially alongthe shaft axis 206. More specifically, the piston 240 may be positionedboth radially and axially along the shaft axis 206 to align proximate tothe plurality of plates 222. Further, between the piston 240 and theplurality of plates 222 may be an apply plate 236. The apply plate mayalso be coupled to the second spline of the outer face 230 and capableof moving axially along the shaft axis 206.

The piston cavity 242 may be fluidly coupled to a fluid passageway (notparticularly shown) defined in the transmission case 212. In onenon-limiting example, the fluid passageway to the piston cavity 242 maybe one of the fluid passageways 140 ₁-140 _(J) described above forFIG. 1. The piston cavity 242 may also be fluidly sealed relative to thesurrounding transmission case 212 by one or more fluid seals 244.Further, the fluid passageway may be fluidly couple to one or morevalves that may selectively direct pressurized fluid through the fluidpassageway and into the piston cavity 242, thereby moving the piston 240in the forward direction.

Between the piston 240 and the apply plate 236 may be a thrust bearing246. In one embodiment, the thrust bearing allows the piston 240 toprovide an axial force in the forward direction without substantiallyrestricting the rotation of the apply plate 236. In this embodiment thepiston 240 may be mounted to the transmission case 212 and therebysubstantially restricted from rotating with the PTO shaft 208. However,the apply plate 236 is splined to the PTO shaft 208 as described in moredetail above. Accordingly, the PTO shaft 208 may rotate relative to thepiston 240. The thrust bearing 246 may allow the relatively stationarypiston 240 to provide an axial force to the rotating apply plate 236without substantially restricting the rotation of the apply plate 236.

A piston spring 248 may also affect the axial alignment of the piston240. More specifically, the piston spring 248 may be coupled to thepiston 240 to provide a rearward force on the piston 240. In thisembodiment, when there is insufficient fluid pressure provided to thepiston cavity 242, the piston spring 248 may force the piston 240 in therearward direction along the shaft axis 206. However, if sufficientfluid pressure is provided into the piston cavity 242, the piston 240may overcome the force provided by the piston spring 248 and moveaxially in the forward direction. In one non-limiting example the pistonspring 248 can be any know mechanical spring such as one or more coilspring, Belleville spring, leaf spring, torsion spring or the any othersimilar mechanical springing system.

In one non-exclusive embodiment the first plurality of plates 224 mayhave a frictional material disposed thereon and the second plurality ofplates 226 may be composed of a material to react with the frictionalmaterial. In this embodiment the first and second plurality of plates224, 226 may substantially lock to one another when a sufficient axialforce presses them together. Accordingly, when pressurized fluid isintroduced into the piston cavity 242, the piston 240 begins to pressthe thrust bearing 246 against the apply plate 236 and the first andsecond plurality of plates 224, 226 may be forced together between theapply plate 236 and the backing plate 232. Further, the first and secondplurality of plates 224, 226 may be pressed together with sufficientforce to substantially transfer the torque of the PTO shaft 208 to thePTO gear 210.

The embodiment of FIG. 2 may be configured to selectively couple the PTOgear 210 to the shaft 208 as described above. More specifically, wheninsufficient fluid pressure is provided to the piston cavity 242, thepiston spring 248 may force the piston 240 in the rearward direction,thereby allowing the first plurality of plates 224 to rotateindependently of the second plurality of plates 226. In thisconfiguration, the PTO gear 210 may not rotate when the PTO shaft 208rotates.

Alternatively, when sufficient fluid pressure is provided to the pistoncavity 242, the opposing force of the piston spring 248 may be overcomeand the piston 240 may move axially in the forward direction, therebysubstantially coupling the first plurality of plates 224 to the secondplurality of plates 226. In this configuration, the PTO gear 210 mayrotate when the PTO shaft 208 rotates.

Referring now to FIG. 3, another PTO clutch assembly 300 is shown. Morespecifically, a rotating clutch assembly 302 is shown in FIG. 3. Thisembodiment may also have a PTO gear 310 disposed radially about theshaft axis 206. The PTO gear 310 may define teeth 311 at a radiallydistal portion and be pivotally coupled to a transmission case 312.Further, the PTO gear 310 may be able to rotate about the shaft axis 206relative to the transmission case 212. In one embodiment, the PTO gear310 may have a gear base 314 defined along a radially inner portion ofthe PTO gear 310. The gear base 314 may extend axially along the shaftaxis 206. A support disc 316 may be coupled to, or integrally formedwith, the gear base 314 at a front portion and extend radially inwardtowards a cylindrical ledge 318. The cylindrical ledge 318 may be spacedabout the shaft axis 206 to have a radius slightly greater than the pumpshaft 204 and/or the PTO shaft 208. Further, the cylindrical ledge 318may extend axially along the shaft axis 206 in the forward direction todefine a coupling surface 320 along a radially outer portion of thecylindrical ledge 318. In one nonexclusive embodiment, a rear portion ofthe cylindrical ledge 318 may be coupled to, or integrally formed with,the support disc 316.

The PTO gear 310 of FIG. 3 may be pivotally coupled about the shaft axis206 by the gear base 314, the support disc 316, and the cylindricalledge 318 in substantially the same way as the PTO gear 210 of FIG. 2.Accordingly, the similarities between the two embodiments are notdiscussed in detail but rather incorporated as applicable for thisembodiment as well.

In one aspect of the embodiment shown in FIG. 3, the clutch assembly 302may be partially disposed radially between the PTO shaft 208 and the PTOgear 310. More specifically, a first plurality of plates 324 and asecond plurality of plates 326 may be axially aligned with the gear base314. Further the first and second plurality of plates 324, 326 may beradially disposed about the shaft 208.

In one non-limiting aspect of this embodiment, the first plurality ofplates 324 may have at least a third tang (not particularly shown)extending radially away from the shaft axis 206. The third tang may besized to correspond with one or more third spline defined in an innerface 328 of the gear base 314. More specifically, the third spline mayallow the third tang, and in turn the first plurality of plates 324, tobe rotationally coupled to the inner face 328 of the gear base 314 whileallowing at least some axial movement along the shaft axis 206.

Similarly, the second plurality of plates 326 may have at least a fourthtang (not particularly shown) extending radially towards the shaft axis206. The fourth tang may be sized to correspond with one or more fourthspline defined in a receiving surface 330 of a hub 332 disposed betweenthe PTO shaft 208 and the first and second plurality of plates 324, 326.More specifically, the hub 332 may have splines along a radially innerportion that correspond with splines on a radially outer portion of thePTO shaft 208. Further, the hub may extend radially away from the shaftaxis 206 to define the receiving surface 330. In other words, the hub332 may be a radial spacer for the receiving surface 330, allowing thesecond plurality of plates 326 to be coupled to the receiving surface330 at a radially outer portion relative to the PTO shaft 208 surface.Further, the fourth spline may allow the fourth tang, and in turn thesecond plurality of plates 326, to be rotationally coupled to thereceiving surface 330 of the hub 332 while allowing at least some axialmovement along the shaft axis 206.

A backing plate 334 may also be coupled to the inner face 328 of thegear base 314. The backing plate 334 may have a forward most axiallocation along the shaft axis 206 where a portion of the support disc316 substantially restricts any further axial movement of the backingplate 334 in the forward direction. Further, the support disc 316 andthe backing plate 334 may be sufficiently sized to resist axial forcesapplied along the shaft axis 206 towards the front direction withoutsubstantially deflecting.

One embodiment of the rotating clutch assembly 302 may include arotating piston assembly 336 disposed radially about the shaft axis 206.The rotating piston assembly 336 may have a housing 338 that furtherdefines an annular piston cavity therein. The housing 338 may have afirst cylindrical segment 346 and a second cylindrical segment 348radially offset from one another about the shaft axis 206. The first andsecond cylindrical sections 346, 348 may be coupled to one another with,or integrally formed through, a piston support disc 350 that extendsradially between the first and second cylindrical sections 346, 348. Inone nonexclusive example, the second cylindrical segment 348 may definea coupling surface 352 along a radially distal portion of the secondcylindrical segment 348. The coupling surface 352 may be a location topivotally couple the rotating piston assembly 336 to the transmissioncase 212. In one nonexclusive embodiment, a bearing 354 or other similarstructure may be positioned between the coupling surface 352 and thetransmission case 212 to allow the rotating piston assembly 336 to moreeasily rotate relative to the transmission case 212.

In yet another aspect of this embodiment, the first cylindrical segment346 may extend axially along the shaft axis 206 to at least partiallycontact a portion of the gear base 314 of the PTO gear 310. Further, thefirst cylindrical segment 346 may be coupled to the gear base 314 so thePTO gear 310 and the rotating piston assembly 336 are substantiallycoupled to one another. In one non-limiting example, the firstcylindrical segment 346 may be coupled to the gear base 314 throughsplines. However, the first cylindrical segment 346 may be coupled tothe gear base 314 using a plurality of different coupling methodsincluding welds, rivets, bolts, adhesives, clamping mechanisms, and/orany other similar coupling mechanisms. Accordingly, this disclosure isnot limited to any particular coupling mechanism.

In the embodiment shown in FIG. 3, the PTO gear 310 and the rotatingpiston assembly 336 may rotate as substantially one assembly relative tothe transmission case 212. Further, the PTO gear 310 and the pistonassembly 336 may rotate with the PTO shaft 208 when the PTO clutchassembly 300 is in the engaged position. Alternatively, the PTO gear 310and the piston assembly 336 may rotate independently of the PTO shaft208 when the PTO clutch assembly 300 is in the disengaged position.

The annular piston cavity may partially encompass a piston 342 that isslidably coupled thereto. More specifically, the piston 342 may bepositioned both radially and axially about the shaft axis 206 to alignproximate to the first and second plurality of plates 324, 326. Further,between the piston 342 and the first and second plurality of plates 324,326 may be an apply plate 344. The apply plate 344 may be coupled to thethird spline of the inner face 328 and capable of moving axially alongthe shaft axis 206.

The piston 342 may selectively move axially along the shaft axis 206 inthe forward direction. More specifically, a piston cavity (notspecifically shown in FIG. 3) may be fluidly coupled to a fluidpassageway 356 defined in the transmission case 212. The piston cavitymay also be fluidly sealed relative to the surrounding transmission case212 by one or more fluid seals 366. Further, the fluid passageway 356may be fluidly coupled to one or more valves of the transmission. Theone or more valves may selectively direct pressurized fluid through thefluid passageway 356 and into the piston cavity, thereby moving thepiston 342 in the forward direction. In one embodiment, the fluidpassageway 356 may be part of the one or more corresponding fluidpassageways 140 ₁-140 _(J) described above.

A piston spring 358 may also affect the axial position of the piston342. More specifically, the piston spring 358 may be coupled to thepiston 342 to provide a rearward force on the piston 342. In thisembodiment, when there is insufficient fluid pressure provided to thepiston cavity, the piston spring 358 may force the piston 342 in therearward direction along the shaft axis 206. However, if sufficientfluid pressure is provided into the piston cavity, the piston 342 mayovercome the force provided by the piston spring 358 and move axially inthe forward direction.

The piston spring 358 may be positioned between a piston disc 360 andthe piston 342. The piston disc 360 may be fixedly coupled to the secondcylindrical segment 348 at axial location proximate to the hub 332. Inone embodiment, a lock ring 362 may be positioned along the secondcylindrical segment 348 to contact and maintain the piston disc 360 in aspecific axial alignment along the shaft axis 206 relative to thetransmission case 312. In one embodiment, the piston spring 358 may be amechanical spring and provide an axial force on the piston 358 in therearward direction by reacting against the axially fixed piston disc360. In this embodiment the piston spring 358 can be any know mechanicalspring such as one or more coil spring, Belleville spring, leaf spring,torsion spring or the any other similar mechanical springing system.

In an alternative embodiment, the rearward force provided to the piston342 may be generated through a hydraulic or pneumatic pressure system.More specifically, instead of positioning a mechanical piston spring 358in the annular piston cavity, one of the plurality of hydraulicpassageways may be a piston return passage 364. In this embodiment, thepiston disc 360 may have one or more fluid seal 366 disposed at an innerradial surface along the second cylindrical segment 348 and one or morefluid seal 366 disposed at an outer radial surface along a portion ofthe piston 342. A balance piston cavity 368 may be an annular fluidchamber defined between the piston disc 360, the piston 342, and thesecond cylindrical segment 348 that only allows substantial fluidtransfer through the piston return passage 364. In this embodiment, whenpressurized fluid is provided to the balance piston cavity 368 throughthe piston return passage 364, it may provide a force on the piston 342towards the rear direction. Accordingly, if the rearward force generatedby the pressurized fluid in the balance piston cavity 368 is greaterthan the forward force generated by the pressurized fluid in the pistoncavity, the piston 342 will move axially to the rearmost position.Alternatively, if the pressurized fluid supplied to the piston cavityprovides a forward force sufficient to overcome the rearward forcegenerated by the pressurized fluid in the balance piston cavity 368, thepiston 342 will move in the forward direction, compressing the first andsecond plurality of plates 324, 326 between the apply plate 344 and thebacking plate 334.

As described in more detail above, the first and second plurality ofplates 324, 326 may substantially lock to one another when a sufficientaxial force presses them together. Accordingly, when pressurized fluidis introduced into the piston cavity, the piston 342 begins to pressagainst the apply plate 344 and the first and second plurality of plates324, 326 are forced together between the apply plate 344 and the backingplate 334. Further, the first and second plurality of plates 324, 326may be pressed together with sufficient force to substantially transferthe torque of the PTO shaft 208, through the hub 332 to the PTO gear310.

The PTO gear 310 may be selectively couple to the shaft 208 as describedabove. More specifically, when insufficient fluid pressure is providedto the piston cavity, or when sufficient fluid pressure is supplied tothe balance piston cavity 368, the piston 342 may be forced in therearward direction, thereby allowing the first plurality of plates 324to rotate independently of the second plurality of plates 326. In thisconfiguration, the PTO gear 310 may not rotate when the PTO shaft 208rotates.

Alternatively, when sufficient fluid pressure is provided to the pistoncavity, the opposing force of the pressurized fluid in the balancepiston cavity 368 may be overcome and the piston 342 may move axially inthe forward direction. The piston 342 may move sufficiently forward andwith enough force to substantially couple the first plurality of plates324 to the second plurality of plates 326. In this configuration, thePTO gear 310 may rotate when the PTO shaft 208 rotates.

In either the embodiment shown and described for FIG. 2 or FIG. 3, theone set of the plurality of plates 224, 226 or 324, 326 can be clutchfriction plates. Clutch friction plates, for example, have been designedwith a carbon fiber material and used in the automotive industry inorder to prevent transmitting the same uneven torque and input rotationfrom internal combustion engines which causes torsional activity anddamage within vehicle transmissions. As a result, similar carbon fiberfriction material may be incorporated into the PTO clutch assembly 200,300 design described herein. Carbon is just one material example, couldbe any type of friction material (cellulose papers, bronze, graphitic,etc.).

Referring now to FIG. 4a , a block diagram 400 illustrates some of theelectrical components of the PTO clutch assembly 200, 300 discussedabove. In one example, a controller 424 may be in communication with aplurality of different sensors. The controller 424 can include a memoryunit for storing a set of instructions that can be executed by aprocessor. The controller 424 can store torque curves, look-up tables,shift curves, threshold values, and any other algorithms, methods,processes, or set of instructions for controlling the PTO clutchassembly 200, 300. In one embodiment, the controller 424 may be thememory unit 144 from the transmission control circuit 142 describedabove.

While specific sensors are discussed herein, this disclosure is notlimited to the particular sensors discussed. Rather, any number and typeof sensors could be used based on the teachings of this disclosure.Further, no particular form of communication between the plurality ofsensors and the controller 424 should be limiting. In one embodiment,the controller 424 may communicate with the plurality of sensors throughone or more wire harness that electrically couples the controller 424 tothe plurality of sensors. In another embodiment, the plurality ofsensors may communicate with the controller wirelessly through one ormore forms of wireless communication. Further still, the signal paths 72₁-72 _(J) described above may be used by the controller 424 here aswell. Accordingly, the particular form of communication between theplurality of sensors and the controller is not limiting.

In one embodiment, a transmission range sensor 402 may be coupled to thecontroller 424. The transmission range sensor can provide a signal tothe controller 424 indicating the position of a transmission selector.In one embodiment, the transmission range sensor 402 may indicatewhether the transmission selector is in a park, reverse, neutral, ordrive position. However, in one embodiment there may be no transmissionrange sensor 402 at all.

A vehicle speed sensor 404 (or speed sensor 150) may also be coupled tothe controller 424. The vehicle speed sensor 404 may indicate to thecontroller 424 the speed of the vehicle at any given time. Further, thecontroller 424 may also communicate with an engine speed sensor 406 thatis coupled thereto. The engine speed sensor 406 may indicate to thecontroller 424 the speed of an engine 426 (or drive unit 102) which, inturn, indicates the rotational speed of the pump shaft 204 and/or thePTO shaft 208.

In one embodiment, a PTO output speed sensor 408 may be coupled to thecontroller 424. The PTO output speed sensor 408 may be coupled to thePTO gear 310, 210 and indicate to the controller 424 when the PTO gear310, 210 is rotating relative to the transmission case 212. Further, thePTO output speed sensor 408 can indicate to the controller 424 theparticular rotational speed of the PTO gear 310, 210. In one embodiment,the PTO output sensor may be a Hall effect type, variable reluctance, orother know sensing technology.

The controller 424 may also be coupled to a transmission temperaturesensor 412 that sends a signal to the controller 424 indicating thetemperature of the fluid within transmission 430. A vehicle grade sensor414 may also communicate with the controller 424 to identify theinclination of the transmission 430 relative to level. The controller424 may also receive a signal from at least one line pressure sensor 416that identifies the hydraulic pressure in at least one respectivehydraulic circuit such as the one or more corresponding fluidpassageways 140 ₁-140 _(J).

The controller 424 can also be in electrical communication with a userinput 418 or other operator controls. The user input 418 can include amanual shift selector, for example, that includes a plurality of usercontrols. The user input 418 can also include a plurality of switches,buttons, levers, joysticks, pedals, etc. One of the plurality ofoperator controls can include a PTO control button. The operatorcontrols can be disposed in a cab of a vehicle to allow the vehicleoperator to manually select one or more of the user control buttons onthe user input 418. In particular, the vehicle operator can select thePTO control button to engage the PTO clutch assembly 200, 300. When theuser input 418 is triggered to an active or enabled state, a signal iselectrically transmitted to the controller 424 to indicate that theoperator desires to activate or enable the PTO clutch assembly 200, 300.

In one embodiment, there can be specific circumstances and conditionsunder which the PTO clutch assembly 200, 300 can be enabled, and thecontroller 424 can store these conditions in its memory unit. Thus, whenthe user input 418 is triggered and the controller 424 receives theindicative signal from the user input 418, the controller 424 candetermine whether appropriate conditions are satisfied before activatingor enabling the PTO clutch assembly 200, 300. Also considered herein aspart of the user input 418 is a touch-screen with a graphical userinterface, push buttons, and any other known device and method forindicating a user preference to a controller.

In one embodiment, the work machine may have outriggers fitted thereto.In this embodiment, the controller 424 may communicate with an outriggersensor 422 that indicates the position of the outriggers to thecontroller 424.

In addition to receiving signals from the plurality of sensors discussedabove, the controller 424 may also send a plurality of signals to aplurality of different components throughout the work machine. Onenonexclusive example of these components is shown in FIG. 4a . However,the components receiving signals from the controller shown and discussedherein are not limiting, rather they are meant only to be non-limitingexamples.

In one embodiment, the controller 424 may send a signal to the engine426 indicating a desired engine speed. The controller 424 may determinethe desired engine speed based on the signals received from theplurality of sensors. In one embodiment, the controller 424 may send asignal to an engine controller (not shown) to increase or decrease therotational speed of the engine 426. Further, the engine speed may bealtered by the controller 424 to generate a desired rotational speed forthe PTO clutch assembly 200, 300.

In another embodiment, the controller 424 may send a signal to a PTOclutch signal 428 to the PTO clutch assembly 200, 300 to engage ordisengage PTO clutch assembly 200, 300. In this embodiment, thecontroller may signal a valve (not specifically shown) of thetransmission to open or close as directed by the controller 424 toengage or disengage the piston 240, 342 of the respective PTO clutchassembly 200, 300.

The controller 424 may also communicate with the transmission 430 basedon the signals monitored by the controller 424. In one embodiment, thecontroller 424 may be a transmission control module that also controlssubstantially all of the components in the transmission. In thisembodiment, the controller 424 may monitor and control both the PTOclutch 428 and the transmission 430. In a different embodiment, thecontroller 424 may send signals to a separate transmission controlmodule to control the transmission 430.

In one embodiment, the controller 424 may monitor and control thecomponents described above based on a control algorithm 432. The controlalgorithm 432 is shown in more detail in FIG. 4b . The control algorithm432 can include a plurality of blocks that are stored in the memory unitand executed by the processor in the controller 424 for operablycontrolling the PTO clutch assembly 200, 300. The plurality of blocksillustrated in FIG. 4b is not intended to be limiting, as one differentexample may include fewer blocks and a second different example mayinclude additional blocks.

Further, while the control algorithm 432 is shown sequentially in FIG.4b , this disclosure is not limited to the specific sequence shown anddescribed. Rather, the sequence of the control algorithm 432 can bearranged in many different orders. Accordingly, this disclosure is notlimited to the order in which steps are shown and described herein butrather considers any number of orders for each step. Further still,there may be no order at all. In one embodiment the controller 424 maybe performing all monitoring and controlling functions at substantiallythe same time.

In one embodiment, the controller 424 may monitor the user input 418 todetermine whether the user input 418 is in an engaged position or adisengaged position (not particularly shown) as indicated by block 434.At this point, if the user input 418 is in the disengage position, thecontroller 424 determines that the PTO clutch assembly 200, 300 shouldbe in the disengaged position and sends signals to the PTO clutch 428and/or the transmission 430 to orient the PTO clutch assembly 200, 300in the disengaged position. The controller 424 may continuously monitorthe user input 418 and not progress to block 440 until the user input418 is in the engaged position.

While monitoring the user input 418 is described in block 434, anotherembodiment may not monitor a user input 418 at all. Rather, thecontroller 424 may determine whether the PTO clutch assembly 200, 300should be engaged based on the readings from the plurality of sensors.In this embodiment, the controller 424 may automatically engage ordisengage the PTO clutch assembly 200, 300 when predefined thresholdsare met by the plurality of sensors. In one non-exclusive example, thecontroller 424 may only engage the PTO clutch assembly 200, 300 when thetransmission range sensor 402 indicates the vehicle is in a parkedtransmission configuration. In yet another embodiment, the controller424 may only engage the PTO clutch assembly 200, 300 when the outriggersensor 422 indicates one or more outriggers are deployed. The controller424 can monitor any number of sensors to determine when to engage thePTO clutch assembly 200, 300 and this disclosure is not limited toexclusively monitoring any particular set of sensors.

In the embodiment of FIG. 4b , once the controller 424 identifies theuser input 418 is in the engaged position, the controller 424 mayperform a basic thresholds check in block 440. The thresholds check of440 may be directed to threshold values for specific sensors. In oneembodiment, block 440 may determine whether a Diagnostic Trouble Code(DTC) sensor 410 indicates a DTC is present. If the controller 424identifies a DTC is present, the controller 424 may not engage the PTOclutch assembly 200, 300. The DTC could indicate any of a plurality ofissues with the transmission 430, the engine 426, or the PTO clutch 428.In one non-exclusive example, the DTC could indicate that the PTO clutch428 is stuck in an engaged or disengaged position. In a differentembodiment, a DTC may indicate that a hydraulic system of thetransmission 430 is not functioning properly. A DTC could indicate anynumber of issues with the vehicle system and this disclosure is notlimited to any specific DTC.

Another basic threshold check of block 440 may be the controller 424monitoring the transmission range sensor 402 to determine whether thetransmission range sensor 402 is indicating a transmission range withina transmission range threshold. In one nonexclusive example, thecontroller 424 may only engage the PTO clutch 428 when the transmissionrange sensor 402 indicates the transmission range is in a “Park” range.In this embodiment, if the transmission range sensor 402 does notindicate to the controller 424 that the transmission is in the “Park”range the controller 424 may not allow the PTO clutch assembly 200, 300to become positioned in the engaged position.

In yet another embodiment of block 440, the outrigger sensor 422 may becompared to an outrigger threshold by the controller 424 before the PTOclutch assembly 200, 300 may be engaged. In this embodiment, theoutrigger threshold may be programmed into the controller 424 toindicate whether outriggers are engaged with the surrounding surface. Inthis embodiment, if the outriggers are not engaged with the surroundingsurface, the outrigger sensor 422 will not indicate to the controller424 that the outrigger threshold requirement is met. Accordingly, thecontroller 424 may not engage the PTO clutch assembly 200, 300 even ifthe user input 418 is in the engaged position.

Block 440 could incorporate many different sensors being monitored bythe controller 424 and compared to a threshold. In one example, thecontroller 424 can compare many different types of sensors to thresholdsas a safety feature prior to engaging the PTO clutch assembly 200, 300.In addition to the above embodiments of sensors monitored in block 440,proximity sensors, weight sensors, motion sensors, and any other type ofsensor may be monitored by the controller 424 prior to engaging the PTOclutch assembly 200, 300. Accordingly, this disclosure is not limited tothe particular sensors described above for block 440 but ratherconsiders utilizing any type of sensor that may be compared to athreshold by the controller 424 prior to engaging the PTO clutchassembly 200, 300.

Referring now to block 436, the controller 424 may monitor the linepressure sensor 416 after the controller 424 determines the user input418 is in the engaged position and all of the threshold conditions ofblock 440 are satisfied. More specifically, the controller 424 maymonitor the line pressure sensor 416 to determine if the line pressuresensor 416 indicates a line pressure greater than a lower line pressurethreshold that has been programmed into the controller 424 or otherwisedetermined. The lower line pressure threshold may be a line pressurethat would be a minimum pressure to properly engage the PTO clutchassembly 200, 300. In one embodiment, if the line pressure is below thelower line pressure threshold, the controller 424 may send a signal tothe solenoid controlling the line pressure, where the signal inindicative of a request for greater line pressure. In this manner, thecontroller 424 can modulate line pressure via its communication with thesolenoid.

In another embodiment, if the line pressure is below the lower linepressure threshold, the controller 424 may execute block 438 to increasethe speed of the engine 426, and thereby increase the line pressureuntil the line pressure is greater than the lower line pressurethreshold or a maximum engine speed threshold is met. In a differentembodiment, if the line pressure is below the lower line pressurethreshold, and cannot be achieved through one of the previouslydescribed methods, the controller 424 may determine the currentconditions are such that it cannot engage the PTO clutch assembly 200,300.

Similarly, in block 442 the controller 424 may monitor the line pressuresensor 416 to determine whether the line pressure is above apre-programmed upper line pressure threshold. The upper line pressurethreshold may be a pressure that adequately engages the PTO clutchassembly 200, 300. Accordingly, any line pressure above the upper linepressure threshold would be an unnecessary burden on the hydraulicsystem. In this embodiment, if the controller 424 identifies that theline pressure is greater than the upper line pressure threshold, thecontroller 424 modulates the line pressure in block 444 until the linepressure is less than or equal to the upper line pressure threshold. Inone embodiment, the controller 424 may modulate the line pressure byadjusting a proportional valve. However, the controller 424 could alsocontrol the line pressure through decreasing engine speed will reducethe pump output flow and decrease the line pressure. and this disclosureis not limited to any one method of modulating the line pressure.

While monitoring the line pressure for both low and high pressures hasbeen described in detail herein, one embodiment may not monitor the linepressure at all. In this non-exclusive embodiment, the controller 424may assume proper line pressure and skip blocks 436 and 442.

In one non-limiting example the line pressure sensor 416 may bemonitored by the controller 424 to ensure that the PTO clutch assembly200, 300 is not damaged. More specifically, the line pressure sensor 416may indicate the hydraulic pressure provided to the piston 342, 240 andfurther applied to the PTO clutch assembly 200, 300. Insufficienthydraulic pressure may cause the PTO clutch assembly 200, 300 to onlypartially engage, causing over-heating of the clutch inadequate linepressure resulting in clutch slip can also result in damage to theconnected PTO device due to improper input speed or operating torque ofthe plurality of plates. Further, it may be inefficient and unnecessaryfor the line pressure to be above the upper line pressure.

The controller 424 may also monitor the transmission temperature sensor412 in block 446. The transmission temperature sensor 412 may indicateto the controller 424 a transmission temperature, i.e., the temperatureof the hydraulic fluid disposed within the transmission 430. In oneembodiment, a transmission temperature threshold may be stored in thecontroller 424. In this embodiment, the controller 424 may comparereadings from the transmission temperature sensor 412 with thetransmission temperature threshold. In another embodiment, iftemperature is outside of the temperature threshold, the controller 424may interpret or determine this condition and not allow any engagement.For example, if the temperature is below a threshold, the controller 424may determine that the system is not up to normal operating temperature.Alternatively, if the temperature is too high (e.g., above a threshold),the controller 424 may determine that there is another concern with thetransmission and not allow PTO operation. In another aspect, however, ifthe controller 424 determines the transmission temperature to be withinthe transmission temperature threshold, the controller 424 may execute acontrolled engagement of the PTO clutch assembly 200, 300 as indicatedby block 450.

The controlled engagement of block 450 may be executed by the controller424 by gradually opening a clutch valve of the transmission 430 thatprovides hydraulic fluid and pressure to the PTO clutch assembly 200,300. The controlled engagement of the PTO clutch assembly 200, 300 mayallow the PTO gear 210, 310 to transition from a stationary staterelative to the PTO shaft 208 (clutch disengaged) to a rotationallycoupled state where the PTO gear 210, 310 rotates at substantially thesame speed as the PTO shaft 208 (clutch engaged).

Once the PTO clutch assembly 200, 300 is engaged via either block 448 orblock 450, the controller 424 may initiate a post engagement sequence452. During the post-engagement sequence 452, the controller 424 maymonitor the PTO output speed sensor 408 to determine a rotational PTOspeed. Further, the controller 424 may monitor the engine speed sensor406 to determine a rotational engine speed. In block 454, the controllermay compare the engine speed to the PTO speed. More specifically,because the PTO clutch assembly 200, 300 should be engaged and thereforerotationally coupled to the PTO shaft 208, the PTO speed and the enginespeed should be substantially the same speed.

If the controller 424 determines that the PTO speed is less than theengine speed by a threshold amount, the controller 424 may execute block456 to increase the line pressure of the system. The controller 424 mayincrease the line pressure of the system by further opening the valve,or any other similar hydraulic control mechanism, to provide anincreased line pressure. The controller 424 may continuously monitor thePTO speed and the engine speed as the valve is further opened in block456. Further, the controller 424 may continue to open the valve untilthe PTO speed is within a threshold of the engine speed or until theline pressure is no longer reduced compared to the hydraulic system(i.e. the valve is fully opened).

If the PTO speed becomes about equal to the engine speed in block 458,the controller 424 will loop back to block 454 and continue to comparethe PTO speed to the engine speed. If the valve is fully opened and thePTO speed is not about equal to the engine speed in block 458, thecontroller 424 may increase the engine speed of the engine 426 as shownby block 460. In one embodiment, by increasing the speed of the engine426, the controller 424 may increase pump flow, and therefore, theoverall available line pressure. More specifically, the hydraulic pump120 may be powered by the engine 426. As the engine speed is increased,the hydraulic pump 120 may provide a greater hydraulic flow to thehydraulic system, thereby increasing the line pressure as the enginespeed is increased.

The engine speed may be increased until an engine speed threshold ismet. The engine speed threshold may be programmed into the controller424 to limit the maximum engine speed. More specifically, as thecontroller increases the engine speed in block 460 to increase the linepressure, the controller 424 may stop increasing the engine speed whenthe engine speed is equal to the engine speed threshold. Further, thecontroller 424 may continuously compare the engine speed to the PTOspeed as the engine speed is increased as indicated by block 462. If thePTO speed becomes about the same as the engine speed, the controller 424may maintain the engine speed and return to block 454.

However, if the controller 424 increases the engine speed to the enginespeed threshold at block 464 and the PTO speed is not about the same asthe engine speed, the controller 424 may disengage the PTO clutchassembly 200, 300 at block 466. More specifically, at block 464 thevalve may be fully opened and the engine speed may be at the enginespeed threshold, thereby providing the highest available line pressurefor the system. If the PTO speed is not about the same as the enginespeed at block 464, the controller 424 may determine that the PTO clutchassembly 200, 300 is slipping and that the PTO clutch assembly 200, 300will be damaged if it is held in the engaged position. Block 466 mayalso send a DTC to the controller 424 indicating an issue and/or cansend a signal to the user that the PTO clutch assembly 200, 300 is notfunctioning properly. The signal sent to the user could be any knownaudible or visual signal.

In another embodiment, the controller 424 may constantly compare theengine speed to the engine speed threshold to determine whether anover-speed condition exists. More specifically, if the controller 424determines the engine speed is greater than the engine speed threshold,the controller 424 may disengage the PTO clutch assembly 200, 300 toprevent a PTO driven assembly damage.

While the post-engagement sequence 452 has been described herein ashappening after a signal to engage the PTO clutch 428 has beentransmitted, the controller 424 may compare substantially all of thesensors described in FIG. 4b to their respective thresholdssimultaneously. Further still, no particular order of executing themethod described above is limiting. Rather, any sequence of monitoringand comparing the sensors discussed is considered herein.

While exemplary embodiments incorporating the principles of the presentdisclosure have been disclosed hereinabove, the present disclosure isnot limited to the disclosed embodiments. Instead, this application isintended to cover any variations, uses, or adaptations of the disclosureusing its general principles. Further, this application is intended tocover such departures from the present disclosure as come within knownor customary practice in the art to which this disclosure pertains andwhich fall within the limits of the appended claims.

The invention claimed is:
 1. A method of selectively controlling a powertake-off (PTO) assembly, comprising: positioning a clutch assemblyradially between a shaft and a PTO gear; operably controlling the clutchassembly with a controller; selectively engaging the clutch assemblywith the controller; wherein the selectively engaging the clutchassembly step comprises: monitoring, by the controller, signals receivedfrom a plurality of sensors; comparing, by the controller, the monitoredsignals with respective signal thresholds; and engaging the clutchassembly when the compared monitored signals are within the signalthresholds; further wherein, the monitoring signals received from theplurality of sensors step comprises monitoring, by the controller, anengine speed sensor, a user input sensor, and a PTO output speed sensor.2. The method of claim 1, further wherein the monitoring signalsreceived from the plurality of sensors step comprises monitoring, by thecontroller, a transmission range sensor, a vehicle speed sensor, a codesensor, a transmission temperature sensor, a vehicle grade sensor, and aline pressure sensor.
 3. The method of claim 1, further comprising:comparing, by the controller, a user input signal generated by the userinput to a user input threshold; wherein, when the user input signal iswithin the user input threshold, the PTO clutch assembly is engaged;wherein, when the user input signal is not within the user inputthreshold, the PTO clutch assembly is not engaged.
 4. The method ofclaim 1, further comprising comparing, by the controller, an enginespeed indicated by the engine speed sensor to a PTO speed indicated bythe PTO output speed sensor when the clutch assembly is in the engagedposition, wherein the controller selectively disengages the clutch whenthe PTO speed is not within a threshold range relative to the enginespeed.
 5. The method of claim 1, further wherein the controller does notengage the clutch assembly when a vehicle speed sensor indicates thevehicle speed within a vehicle speed range.
 6. A method of controlling apower take-off (PTO) assembly of a transmission, comprising: providing auser input, an engine, the transmission including a shaft, a hydraulicsystem, and fluid within the hydraulic system having a line pressure, acontroller including a memory unit and a processor, and the PTO assemblyincluding a PTO gear, a PTO output sensor, and a clutch assemblypositioned between the PTO gear and the shaft; determining, by thecontroller, when a user input has been received; comparing, by thecontroller, the line pressure of the fluid to a pressure thresholdstored in the memory after the user input has been received; engagingthe clutch assembly, by the controller, when the line pressure is abovethe pressure threshold; detecting PTO speed with the PTO output sensor;and comparing, by the controller, an engine speed of the engine to thePTO speed when the clutch assembly is engaged; wherein, if a differencebetween engine speed and PTO speed is not within a predefined speedthreshold value, the controller increases the line pressure.
 7. Themethod of claim 6, further comprising increasing engine speed if theline pressure is below the pressure threshold.
 8. The method of claim 6,wherein the engaging the clutch assembly step comprises opening a valveof the transmission.
 9. The method of claim 6, further wherein thecontroller compares the line pressure to a second pressure thresholdstored in the memory, wherein when the line pressure is greater than thesecond pressure threshold, the controller modulates the valve in thetransmission until the line pressure is less than the second pressurethreshold.
 10. The method of claim 6, further comprising increasing theengine speed, by the controller, when clutch assembly is in the engagedposition and the PTO speed is less than a PTO threshold.
 11. The methodof claim 6, further wherein: the controller compares the engine speed toan engine speed threshold stored in the memory of the controller; andthe controller disengages the clutch assembly if the monitored enginespeed is greater than the engine speed threshold.
 12. A method forcontrolling a power take-off (PTO) assembly of a transmission,comprising: providing a controller, a user input, a pressure sensor, avalve, a shaft speed sensor, and the PTO assembly including a PTO gear,a PTO speed sensor and a clutch assembly disposed radially between thePTO gear and a shaft of the transmission; receiving, with thecontroller, a command from the user input indicating a desiredengagement of the clutch assembly; comparing a line pressure detected bythe pressure sensor to a pressure threshold stored in the controller;controlling the valve, with the controller, to restrict the clutchassembly from engaging the PTO gear when the line pressure is less thanthe pressure threshold; comparing a PTO speed measured by the PTO speedsensor to a shaft speed measured by the shaft speed sensor with thecontroller when the clutch assembly is in an engaged position; anddisengaging the clutch, with the controller, when the comparing a PTOspeed step indicates the PTO speed is not substantially the same as theshaft speed.
 13. The method for controlling a clutch assembly of claim12, further comprising controlling, with the controller, an input speedand increasing the input speed when the line pressure is less than thepressure threshold and the input speed is less than an input speedthreshold.
 14. The method of controlling a clutch assembly of claim 12,further comprising increasing the line pressure when the shaft speed isgreater than the PTO speed.
 15. The method of controlling a clutchassembly of claim 12, further comprising reducing the line pressure whenthe line pressure is above a second pressure threshold.
 16. The methodof controlling a clutch assembly of claim 12, further comprisingrestricting the clutch assembly from engaging unless a transmissionrange selector is within a transmission range threshold.
 17. The methodof controlling a clutch assembly of claim 12, further comprising:providing a vehicle grade sensor that communicates the grade of thevehicle to the controller; and restricting the clutch assembly fromengaging when a vehicle grade sensor value is not within a vehicle gradethreshold.
 18. The method of controlling a clutch assembly of claim 12,further comprising: monitoring a transmission temperature; providing aninstantaneous full line pressure to engage the clutch assembly when thetransmission temperature satisfies a temperature threshold; andproviding a gradual increase to line pressure to engage the clutchassembly when the transmission temperatures does not satisfy thetemperature threshold.
 19. The method of controlling a clutch assemblyof claim 12, further comprising: monitoring an outrigger; and engagingthe clutch assembly only when the outrigger is in an extended position.20. A method of selectively controlling a power take-off (PTO) assembly,comprising: positioning a clutch assembly radially between a shaft and aPTO gear; operably controlling the clutch assembly with a controller;selectively engaging the clutch assembly with the controller; whereinthe selectively engaging the clutch assembly step comprises: monitoring,by the controller, signals received from a plurality of sensors;comparing, by the controller, the monitored signals with respectivesignal thresholds; and engaging the clutch assembly when the comparedmonitored signals are within the signal thresholds; further wherein, thecontroller does not engage the clutch assembly when a vehicle speedsensor indicates the vehicle speed is within a vehicle speed range.